This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. One of the most powerful tools for analyzing ion channel structure/function has been the identification of natural toxins agonists and antagonists. Several organisms produce small protein toxins that act on ion channels and aid in prey capture or defense. We propose to study toxin interaction with the ion channel TRPV1. We will use MALDI mass spectrometry to assess the molecular composition of toxins isolated by reverse phase chromatography. The UCSF Mass Spectrometry Facility will assist in the collection to determine the molecular weight of isolated toxins.